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Vitamin B12 deficiency anemia

Megaloblastic macrocytic anemia

 

Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues. There are many types of anemia.

Vitamin B12 deficiency anemia is a low red blood cell count due to a lack (deficiency) of vitamin B12 .

Causes

 

Your body needs vitamin B12 to make red blood cells. In order to provide vitamin B12 to your cells:

  • You must eat plenty of foods that contain vitamin B12, such as meat, poultry, shellfish, eggs, and dairy products.
  • Your body must absorb enough vitamin B12. A special protein, called intrinsic factor, helps your body do this. This protein is released by cells in the stomach.

A lack of vitamin B12 may be due to dietary factors, including:

  • Eating a poorly planned vegetarian diet
  • Poor diet in infants
  • Poor nutrition during pregnancy

Certain health conditions can make it difficult for your body to absorb enough vitamin B12. They include:

  • Chronic alcoholism
  • Crohn disease, celiac disease, infection with the fish tapeworm, or other problems that make it difficult for your body to digest foods
  • Pernicious anemia, a type of vitamin B12 anemia that occurs when your body destroys cells that make intrinsic factor
  • Surgery that removes certain parts of your stomach or small intestine, such as some weight-loss surgeries
  • Taking antacids and other heartburn medicines for a long period of time

 

Symptoms

 

You may not have symptoms. Symptoms may be mild.

Symptoms can include:

  • Diarrhea or constipation
  • Fatigue , lack of energy, or lightheadedness when standing up or with exertion
  • Loss of appetite
  • Pale skin
  • Problems concentrating
  • Shortness of breath , mostly during exercise
  • Swollen, red tongue or bleeding gums

If you have low vitamin B12 level for a long time, you can have nerve damage. Symptoms of nerve damage include:

  • Confusion or change in mental status ( dementia ) in severe cases
  • Depression
  • Loss of balance
  • Numbness and tingling of hands and feet

 

Exams and Tests

 

The health care provider will perform a physical exam. This may reveal problems with your reflexes.

Tests that may be done include:

  • Complete blood count ( CBC )
  • Reticulocyte count
  • Lactate dehydrogenase ( LDH ) level
  • Vitamin B12 level
  • Methylmalonic acid ( MMA ) level

Other procedures that may be done include:

  • Esophagogastroduodenoscopy ( EGD ) to examine the stomach
  • Enteroscopy to examine the small intestine
  • Bone marrow biopsy if the diagnosis is not clear

 

Treatment

 

Treatment depends on the cause of B12 deficiency anemia.

The goal of treatment is to increase your vitamin B12 level.

  • Treatment may include a shot of vitamin B12 once a month. If you have a very low level of B12, you may need more shots in the beginning. It is possible you may need shots every month for the rest of your life.
  • Some people may also need to take vitamin B12 supplements by mouth.

Treatment may no longer be needed after Crohn disease, celiac disease, or alcohol use is properly treated.

Your provider will also recommend that you eat a variety of foods.

 

Outlook (Prognosis)

 

People with this type of anemia often do well with treatment.

Long-term vitamin B12 deficiency can cause nerve damage. This may be permanent if you do not start treatment within 6 months of when your symptoms begin.

 

Possible Complications

 

A woman with a low B12 level may have a false positive Pap smear. This is because vitamin B12 deficiency affects the way certain cells (epithelial cells) in the cervix look.

 

When to Contact a Medical Professional

 

Call your provider if you have any of the symptoms of anemia.

 

Prevention

 

You can prevent anemia caused by a lack of vitamin B12 by eating a well-balanced diet.

Shots of vitamin B12 can prevent anemia after surgeries known to cause vitamin B12 deficiency.

Early diagnosis and prompt treatment can reduce or prevent complications related to a low vitamin B12 level.

 

 

Open References

References

Antony AC. Megaloblastic anemias. In: Hoffman R, Benz EJ Jr, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice . 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 37.

Bunn HF. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 158.

 
  • Megaloblastic anemia - view of red blood cells

    Megaloblastic anemia - view of red blood cells - illustration

    This picture shows large, dense, oversized, red blood cells (RBCs) that are seen in megaloblastic anemia. Megaloblastic anemia can occur when there is a deficiency of vitamin B-12.

    Megaloblastic anemia - view of red blood cells

    illustration

  • Hypersegmented PMN (Close-up)

    Hypersegmented PMN (Close-up) - illustration

    This image shows a large polymorphonuclear leukocyte (PMN) with multiple discretely-identifiable nuclear lobes. It can be seen in megaloblastic anemias. Normal PMN's have less than or equal to 5 lobes.

    Hypersegmented PMN (Close-up)

    illustration

    • Megaloblastic anemia - view of red blood cells

      Megaloblastic anemia - view of red blood cells - illustration

      This picture shows large, dense, oversized, red blood cells (RBCs) that are seen in megaloblastic anemia. Megaloblastic anemia can occur when there is a deficiency of vitamin B-12.

      Megaloblastic anemia - view of red blood cells

      illustration

    • Hypersegmented PMN (Close-up)

      Hypersegmented PMN (Close-up) - illustration

      This image shows a large polymorphonuclear leukocyte (PMN) with multiple discretely-identifiable nuclear lobes. It can be seen in megaloblastic anemias. Normal PMN's have less than or equal to 5 lobes.

      Hypersegmented PMN (Close-up)

      illustration

    A Closer Look

     

    Self Care

     

      Tests for Vitamin B12 deficiency anemia

       
       

      Review Date: 2/1/2016

      Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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